1. Field of the Invention
The present invention relates to a holding structure for holding a member to be held in an external cabinet comprising a combination of a first cabinet and a second cabinet. In addition, the present invention relates to a projection display device for enlarging and projecting an image on a display element on a projection plane.
2. Description of the Related Art
Projection display devices (hereafter, referred to as “projectors”) for enlarging and projecting an image on a display element (liquid crystal panel, or the like) on a projection plane (screen, or the like) have been commercialized and widely used. In the projectors of this sort, it is desirable to reduce a distance between the screen and the projector body.
To attain this, an arrangement for oblique projection may be used in which a projection optical system is wide-angled, and at the same time, a direction of projection light traveling is oblique to an optical axis of the projection optical system. For example, when a wide-angle lens with a large view angle is used as the projection optical system, and a display element and a screen are shifted in opposite directions to each other with regard to the optical axis of the projection optical system, a projection distance is shortened, and at the same time, oblique projection without distortion can be achieved. However, with the arrangement as mentioned, a wider-angle lens with a larger view angle is necessary, and therefore, increased costs due to a large-sized lens and a large-sized projector body pose a problem.
On the other hand, for realization of the reduced projection distance, such an arrangement is also considered that a projection lens section and a mirror are used as a projection optical system, an image on a display element is formed as an intermediate image between the projection lens section and the mirror, and the intermediate image is then enlarged and projected by the mirror.
In general, the projector of this type is designed to have such an arrangement that a projection lens unit and a mirror are mounted in a housing, and the housing is held in an external cabinet. In this case, one idea is to use a structure for holding an optical engine as a structure for holding the housing. In general, in the structure for holding the optical engine, a spacer is attached to a bottom face of a chassis, the optical engine that is a member to be held is placed on the spacer via an elastic bush, and the optical engine is threaded to the spacer from the above. With this holding structure, it is designed that the optical engine is held only by the bottom face of the chassis via the elastic bush and spacer. That is, the optical engine is held by a so-called planar structure.
However, the projection optical system where the projection lens unit and the mirror are mounted in the housing is far heavier as compared to the optical engine. Therefore, when such as projection optical system, i.e., a heavier member to be held, is held by the holding structure of the above-mentioned optical engine, and when an impact is applied to the projection optical system, deformation in the bottom face of the external cabinet for holding the projection optical system might be caused.